Today, Trans Urethral Resection of the Prostate (TURP) is the standard therapy for Benign Prostatic Hyperplasia (BPH) and prostate cancer. TURP employs an electrosurgery device and resectoscope for the surgical removal of prostatic tissue through the urethra. Approximately 400,000 prostatectomies are performed annually in the United States at a cost of nearly five billion dollars. Immediate postoperative morbidity is about 18% for this procedure. TURP generally requires 5 days of hospitalization and 6 weeks for recovery. Complications of TURP include blood loss, impotence, and incontinence. The high cost of TURP and its associated morbidity have given urologists a strong incentive to seek alternate therapies for BPH. Alternative new technologies are being developed as minimally invasive means for the treatment of BPH. These technologies include lasers, microwave, ultrasound. stents, balloon dilatation, and drugs.
MERCK's Proscar.TM., a drug approved in 1992, requires more than six months to produce a therapeutic effect and is limited in its utility to probably 25% of BPH patients. Balloon dilatation products have been on the market for several years but have proven unsuccessful.
Stents being developed for the treatment of BPH are undergoing clinical trails. The initial clinical results demonstrate the incidence of significant complications, such as stent migration and increased frequency of urination. Ultrasound ablation and microwave have demonstrated a lesser degree of improvement in patient symptoms when compared to TURP.
Laser ablation offers a viable alternative to TURP and other therapeutic modalities for the treatment of BPH. Laser ablation provides means for achieving deep and controlled depth of penetration of laser energy into prostatic tissue. Thus, a large volume of the diseased prostate can be ablated without causing damage to surrounding tissues.
Clinical results from a prospective randomized clinical trail of laser ablation compared to TURP were presented at the 1993 meeting of the American Urological Association (AUA). These results indicate that laser ablation is comparable to TURP in terms of the improvement in urinary flow rate and symptom scores, but is superior to TURP with respect to the risk of impotence and blood loss. A very significant advantage of laser ablation is the cost effectiveness of this procedure. When compared to TURP, Laser ablation was shown to shorten the time for return to normal activity from 6 weeks to 1 week; shorten hospital stay from 3.2 days to 1.6 days; and shorten intraoperative time from 22 minutes to 12 minutes.
Nd:YAG lasers are the energy source of choice for this procedure. These lasers operate at the near infrared zone of the spectrum at a wave length of 1.06 micrometers. This wave length is known to have a very high scattering coefficient in water and soft tissue, and accordingly an ability to penetrate deep into the tissue without being absorbed at the surface. Laser energy causes thermal coagulation necrosis which results in tissue absorption and sloughing within four weeks from the laser treatment.
Nd:YAG lasers are solid state user-friendly systems that have been used in hospitals and approved by the FDA for nearly 15 years. It is estimated that there is an installed base of over 2,000 Nd:YAG lasers in U.S. hospitals today. Many of these lasers can provide the energy required for laser ablation of the prostate.
Commercially available laser catheters such as those marketed by C. R. Bard and Myriadlase utilize a metal reflector for diverting the laser beam into a lateral direction (U.S. Pat. No. 5,242,437-Everett et al). These catheters have a tendency to overheat at the catheter tip, which could lead to tip detachment during clinical use, thus raising a serious safety concern. Other commercial laser catheters such as those marketed by Laserscope and Heraeus Surgical employ the principle of Total Internal Reflection (TIR) at the distal end of the fiberoptic by providing a beveled surface at the tip of the fiber or adding a prism to that fiber (i.e., U.S. Pat. No. 4,740,047-Abe et al). These surfaces or prisms cause the laser beam to exit from the side of the fiberoptic. These catheters also experience overheating and unpredictable performance. It is, therefore, desirable to have a fiberoptic delivery system that provides the means for safe and effective transfer of the laser energy to specific area of the patient being operated on.
The present invention solves the above set forth problems and meets the foregoing desires by the provision of means and methods for the ablation of prostatic tissue in a living human by subjecting the prostate, at a selected site, to a laser beam having sufficient power, and for a sufficient time to create a deep lesion at such site. The site be treated can be identified and monitored by endoscopic examination during the time of laser ablation. Delivery of the laser energy from the side of the catheter is accomplished without the use of reflector surfaces, prisms, or beveled surfaces, thus solving the problem of heat generation, which can cause device failure and unpredictable performance. Furthermore, the laser energy can be emitted continuously with the method disclosed herein since the catheter is rotated in an at least one direction, and preferably in an oscillatory manner, in both the clockwise and counter clockwise directions. This rotational method prevents localized overheating of the tissue by allowing adequate time for the tissue near the surface of the urethra which has been treated to cool down while the laser energy is applied to adjacent sites. This rotational method, therefore, prevents subsurface ablation ("popcorn effect") and subsequent bleeding, which is a common clinical complication in today's laser ablation of the prostate. Localized irrigation is provided at the tip of the catheter to help maintain the laser output and assist in cooling the surface of the prostatic urethra during laser delivery.
It would also be desirable to have a device and method for vaporizing prostatic tissue following the laser coagulation procedure in order to create a definitive lumen that can facilitate urination and eliminate the need for placing a urinary drainage catheter. Currently, laser coagulation of the prostate causes edema (swelling) of the prostate at the treatment site. As a result, the treated tissue obstructs the urethra and makes it difficult for the patient to urinate.
The present invention satisfies the foregoing desires by providing means and method for vaporization of prostatic tissue as the sole therapy, or as an adjunct to laser coagulation or other interventional procedures, such as microwave therapy.